regular*
Here are some words that match your criteria:

- regular
- regular army
- regular convex polyhedron
- regular convex solid
- regular dodecahedron
- regular hexagon
- regular hexahedron
- regular icosahedron
- regular octahedron
- regular payment
- regular polygon
- regular polyhedron
- regular recurrence
- regular tetrahedron
- regularisation
- regularise
- regularised
- regularity
- regularization
- regularize
- regularized
- regularly